Sinclair



Sept. 9, 1952 H. SINCLAIR POWER-TRANSMISSION MECHANISM Original Filed Sept. 14, 1948 INVENTOR Hamid 52110122 ATTORNEYS Sept. 9, 19 H. SINCLAIR POWER-TRANSMISSION macmmrsu original Filed Sept. 14, 1948 4 Sheets-Sheet 2 A H a H WW8 mv w $1 m \I. a I| w 68 7 9 H w a 5 M :1

ls w I z 5 5 I19 INVENTOR Hamlddz'rwlazin BY 42: m W M ATTORNEYS Sept. 9,1952 H, smc Re. 23,549

POWER-TRANSMISSION MECHANISM Original Filed Sept. 14, 1948 4 Sheets-Sheet 3 II M I;

[11E EM it I] lhil I] III mveu-ron Haroki Sinai (11,1

BY 2 7M "M ATTORNEY:

' improved Reassessmen UNlTED STATES PATENT OFFIC 2am I one No. "um. ems July 1951. Serial I No. ltluf ptember 14. 1043. Application Ierrelssuehly I, 1952, Serial No. 391,415

1: Claims. (01. 14-439) latter in heavy brackets I: II appears in the original patent but forms no part of this refill M: matter printed in italics indicates the additions made by reissue.

' substantial driving torque in only one direction of rotation, a driven member required to be driven alternatively in the forward and backward directions of rotation at will. and gearing providing in parallel between the driving and driven verse-drive power path, said paths having respectively selecting clutches operable for establishingithe drives through them.

One object ofthis invention is arrangement of power-ton mechanism of the kind hereinbefore specified, whereby the driven member, when connected to l a load having a high inertia.'can be easily braked by the application of countertorque derived from the driving member or whereby it can be driven in the reverse direction.

According to this invention, a power-transmission mechanism of the kind hereinbeior'e specified includes auxiliary driving means capable, while the driven member is running, and on disengagement of the engaged selecting clutch, of accelerating the driving member in the reverse direction to a speed suillcient to synchronise the selecting clutch that was not previously engaged.

when the auxiliary driving means have acted so to reverse the rotation of the driving member,

energized for running in its forward direction while it is being rotated backwards by the forward rimning driving member. In this case. the sequence of operations required to change the rotation of the driven shaft from forwards to backwards (or vice 'versa) consists in interrupting the supply of driving fluid to the main turbine and to provide anbers a forward-drive power path and a redrive) selecting clutch. the driven member of which is kept in rotation by the inertia of the load on the system, next permitting or causing engagement of the reverse-drive (or forwarddrive) selecting clutch and de-energising the auxiliary drive means, and finally re-adgnittingdriving fluid-to the main turbine so as toarrest its backward rotation and to cause it to accelerate in its driving direction while driving the driven shaft backwards (or forwards).

The foregoing statement that the driving 'member is capable of exerting substantial driving torque in only one direction of rotatioii is intended to exclude the shaft of a reversing steam turbine such as is ordinarily. used ,for marine propulsion to develop not less than about one-half of the power of the main turbine. It is not, however, intended to exclude an arrangeof an elastic fluid turbine and in which the auxiliary driving means consist of an elastic fluid permitting or causing disengagement or preselecting for disengagement the forward-drive (or backward-drive) selecting clutch, thereafter energising the auxiliary drive prime mover which operates in arrest the main turbine and thereafter 'to accelerate it up to the speed necessary to synchronise the reverse-drive ,(or forwardturbine in the same casing as the main turbine. The distinction is that, in the known arrangement, the reversing turbine is able to perform a similar duty to the main turbine, e. g. propel a. ship; whereas in the new arrangement in question the auxiliary turbine is required only to motor the main turbine and is therefore designed to give only a small fraction of the power of the latter.

In an alternative arrangement, where it is inconvenient to stop the prime mover, the driving member may be the driven part of a. preferably controllable hydraulic turbocoupling or a pref-- erably controllable electric slip coupling the driving part of which is drivably connected to the prime mover, e. g. an elastic fluid turbine or a non-reversing reciprocating internal-combustion engine. In this case the auxiliary driving means may be a power take-ofl, including an auxiliary slipable coupling, from the prime mover arranged inparallel with the main hydraulic turbo-coupling or electric slip coupling. The sequence of operations required to change the rotation of the driven shaft from forwards to reverse (or vice versa) is generally as described in the foregoing and consists briefly in disengaging the main coupling (if controllable) while the turbine or engine is allowed to run substantially idly, thereafter engaging the auxiliary slipable coupling so that the driven part of the main coupling is arrested and then accelerated up to the speed necessary to synchronise the reverse-drive (or forward-drive) selecting clutch, the driven member of which is kept in rotation by the inertia of the s load on the system, next engaging the reversedrive (or forward-drive) clutch, and disengaging the auxiliary coupling, and finally progressively rc-engaging the main pable coupling (if controllable) while the pow tput of the turbine or engine is increased. If the main coupling is a hydraulic turbo-coupling, it need not be control-.-

tively to mesh the lable provided it is of the kind wherein the torqueis substantial relative rotation between the clutch elements; thus for example the clutches may be of the synchro-self-shifting type or of the balked Jaw type. Alternatively the selecting clutches may be of a type which is not adapted without prohibitive deterioration to couple the driving and driven members under conditions such that there is substantial relative rotation between the clutch elements; thus for example the clutches may be of the magnetically actuated friction type having a high loading per unit area of the friction surfaces and hence a small power-absorbing capacity.

The term clutch of the synchro-self-shifting type here means a mechanism having a first member which is provided with a set of jaw clutch teeth and which may be for example the drivlnginember or the driven member of the mechanism, a second member, which may .be the driven member or the driving member respectively, and which is rotatable relatively to the first member, an intermediate member which is provided with a set of Jaw clutch teeth and which is drivably connected to the second member by means constraining the intermediate member to slide relatively to the first and second members into and out of meshing engagement with the first member on reversal of torque throughv the mechanism, and an auxiliary driving connection of the ratchet type including a pawl mounted on one of the first and intermediate members and adapted to co-operate with teeth on the other of these members when these members are dis- 0 engaged, the pawl being operative to transmit torque in such a sense between the first and intermediate members that the second and intermediate members co-operate to cause the intermediate member to slide in the axial direction such that the sets of clutch teeth interengage cleanly under the registering action of the pawl. The second member may be a shaft provided with helical splines, the intermediate member having internal splines co-operating with the shaft splines, as described in U. S. patent specification No. 2,202,271. Alternatively the second member may be a helical-tooth gear wheel, the intermediate member, which is co-axial with the first member, including a helical-tooth gear wheel meshing with the first-mentioned gear wheel and provided with clutch teeth adapted to engage the clutch teeth on the first member, as described in U. S. patent specification No. 2,320,757. Where selecting couplings of the synchro-self-shifting type,are used, preferably the element of each coupling that moves axially to engage the coupling jaws is capable of moving to either side of the engaged position and is provided with two sets of synchronising pawls which serve respecthes .shaft 2| and having sane axially movable element cleanly when moved from the two sides respectively, the coupling also having a controllable stop member which can be operated toprevent the axially movable element from moving beyond the engaged position when the driving element of the coupling tends to rotate forwards relatively to its driven element. In order to avoid continuous ratcheting of the pawls of one of thesync chro-self-shifting couplings while the other is transmitting the drive, preferably each of the said axially movable elements is capable ofmoving, in

response to forward rotation of the driving element of the coupling relative to its driven element, to a disengaged position such that both sets of pawls are inoperative. and control means serve to shift the said axially movable elements from the said disengaged position to a position in which the appropriate set of pawls is operative.

Two embodiments of the invention will be described by way of example and with reference tomthle accompanying diagrammatic drawings, in w c Fig. l is a plan, partly in section, of a marine power plantem odying an elastic fluid turbine. and suitable for use in combination with gasgenerators as a source of power gas, capable of givingthe necessary range of volume and pressure during all the operations of a reversing cycle in normal manoeuvring and in emergency conditions.

"Fig. 2 is a section on the line 2-4 in Fig. 1.

Fig. 3 is a plan of control mechanism for the reversing gear of the same plant.

Figs. 4, 5 and 6 are diagrams showing the relationship between a control lever in Fig. 3 and parts actuated by it. v

Figs. 7, 8, 9 and 10 are diagrams illustrating the operation of a synchro-self-shifting coupling forming part of the same plant, the upper part of each of these figures being a sectional elevation of one halfof the coupling and the lower part a developed view showing control dogs.

Fig. 11 is a sectional plan of a marine reversing gearing suitable for use with an intemal-combustion engine.

Fig. 12 is a sectional elevation of a coupling connecting thev gearing shown in Fig. 11 to the engine.

In the marine turbine installation shown in Fig. 1, a main turbine 20 has its rotor coupled to a driving shaft 2| carried in bearings 12 and 23. The shaft BI is the aforesaid driving member and on it is rotatably mounted an ahead pinion 2|. An astern pinion II is rotatably mounted on a lay shaft ll carried in bearings 21 and 28. Gear wheels 2! and II respectively fast on the shafts 2i and II and meshing together constrain these shafts to rotate at all times in opposite directions. The pinions 24 and 25 are in constant mesh with an output gear wheel 3| fast on the propeller shaft itllvnvhich is the aforesaid driven member of The ahead pinion 24 can be clutched to the driving shaft II, by a synchro-self-shifting coupling including an internally helically splined intermediate member 33 (hereinafter referred to as a nut) slidable on right-handed helical splines, indicated diagrammatically by 34, on the driving jaw clutch teeth 35 engageable with jaw-clutch teeth 36 on a ring 31 rigidly coupled to the pinion 24 by a tubular distance piece 30. The nut II can move axially from a first, limit position I in which its teeth 35 are'on the right-hand side of the jaw-clutch teeth It on 8 the pinion. through a second position 2 in which it appears in Fig. 1 and in which the law-clutch teeth' II and I4 are in mesh, thence through a third position 3 in which the nut teeth ii are on the other side of the Pinion jaw-clutch teeth to a four limit position -4. Two sets of pawls II and lrfl lg. 2) operate in known manner to register the jaw-clutch teeth It and 34 for clean engage-' from the first towards the third position. ;This

' stop consists of a control sleeve 4| having straight internal splines 42-slidably engaged with external splines 43 on the nut 33. Dogs 44 on the interior of the sleeve 4| co-operate with dogs 45 on a collar 46 rigid with the shaft II. The control sleeve 4! has a circumferential groove 41 engaged by a yoke 48 (Fig. 3) coupled by preselector means to a control lever. These means include two spaced hollow bosses 49 and 50 rigid with the yoke 48 and slidable on a selector rod ll which is in turn slidable in a gear case I! by means of the control lever 53. The selector rod Ii has a longitudinal diametrical slot 54 through which pass pins 55 and 56 fast respectively in collars 51 and 58 slidable on the rod 5| between the bosses 49 and iii. A helical compression spring 59 urges the collars 51 and 58 apart.

The astern pinion 25 (Fig. 1) can be clutched to the lay shaft 26 by a synchro-self-shifting coupling similar to that on the driving shaft 2|, except that its nut runs on left-handed splines and that the directions in which its pawls face are reversed. Parts of the astern coupling corresponding to those of the ahead coupling are denoted by the same reference numerals, followed by the reference letter A. The control sleeve 4 IA of the astern coupling is coupled to the abovementioned control lever 53 by preselector means similar to those for the ahead control sleeve and denoted by the same reference numerals followed by the reference letter A. The bosses 49 and 49A are connected by a floating lever 60 fitted with an indicator pointer Bi which follows up the move.-

mentof the control. lever 53 when the control sleeves have executed their preselected axial displacements.

The control sleeves have four positions of axial displacement. In Figs. 1 and 3 the ahead control sleeve 4! appears in the "ahead position denoted by Ah. It can be shifted to the left (Fig. 1) from this position through a midposition M and a, free position F to an -astern position As. The astern control sleeve 4IA appears in Figs. 1 and 3 in the ahead position Ah and can be shifted to the right (Fig. 1) from this position through the free position F and the midposition M to the astern position As. Figs. 4 to 6 show diagrammatically the relative positions of the control lever 53 and the control sleeves after the preselector means have operated. From Fig. 5 it is apparent that, when the control lever is in its midposition, both control sleeves are in their midpositions M. When the control lever is in the ahead position 'as in Fig. 4, both control sleeves are in position Ah, and the spring coupling of the ahead preselector means is strained as shown in Fig. 3.

Likewise, when the control lever is in the astern' position as in 6, both control sleeves are in position As, and the spring coupling of the astern preselector means is strained.

An aurdliary turbine 42 (Fig. l) isconnected positively to the driving shaft II and provided with a stop valve 43 for controlling the supply of working fluid to it.

A'movable abutment member is arranged to preventthe control sleeves 4| and 4 IA from moving to the left (Fig. 1) beyond the free'position F so long as the valve 63 is open. As shown diagrammatically in Fig. 3, this abutment, denoted by 84, is a plunger rigid with a piston 65 slidable. in a cylinder 46 of a fluid pressure motor. A source of fluid under pressure is connected to a supply port ll of a control valve it having an outlet port-69 and a connection III to the cylinder 66. The valves and 68 are coupled by a system H in such a manner that, when the valve 43 is closed, as shown, the cylinder 66 communicates with the outlet port 89, and that, when the valve 83 is open, the cylinder .64 communicates with the supply portiil and the piston l5 and the abutment 84 are forced outwards. Lugs 12 and "A on the yokes 44 and.48A co-operate with the abutment 54 when the latter is moved outwards to prevent the control sleeves 4| and A from moving respectively towards the positions As and Ah beyond the positions F.

Operation of the mechanism will be explained by imagining that the ship is moving ahead under power, the control mechanism being in the position in which it appears in Figs. 1, 3 and 4. The forward direction of rotation of the mechanism is indicated by arrows in Fig. 1. Under these conditions the dogs are in driving engagement with the dogs 44 in the control sleeve 4|, as shown in Fig. 7, so that the nut 33 is prevented from moving to the left beyond position '2 along the helical splines 34; its teeth 35 are therefore kept in engagement with the j aw clutch teeth as of the ahead pinion. The dogs 45A are ahead to 'astern,fl the supply of driving fluid is cut oil from themain turbine 20 and applied to the auxiliary turbine 62 and the control lever 53 is moved from the ahead position to the astern position. The operation of the valve control system 11 (Fig. 3) causes the abutment 64 to be moved outwards. The slowing down ofthe turbine shaft 2i relatively to the ahead pinion 24, which is kept rotating by the way on the ship, cause the ahead coupling nut.33 to move to its first position (Fig. 8), and the removal oftorque load from the dogs 44 of the control sleeve 4| allows this sleeve to be shifted by the preselector spring 59 to position F in which it is arrested by engagement of the lug 12 with the abutment 64. The astern control sleeve MA is shifted by its preselec-tor spring 59A (or by the abutment 64, depending on which operates first) to position F, its front end engaging the flange portion of the nut 33A and moving it along the splines 34A to its third position in which the pawls 40A ratchet overthe jaw clutch teeth 36A of the astern pinion. Further shifting of the control sleeve A is prevented by engagement of the front cause faces of its dogs "A with the rear faces of the dogs "A.

The auxiliary turbine 32 thereafter reverses the rotation of the main turbine, and when the turbines have accelerated in the reverse direction to a speed sumcient to synchronise the astern coupling, the pawls "A will engage teeth 33A and cause the nut 33A to move along the splines to its first position. This movement of the nut helically on the shaft 23 causes the dogs A to rotate clear of the dogs' "A so that the control sleeve CIA is shifted by the spring 33A to position As. The resulting movement of the pointer GI indicates to the operator that the supply of driving fluid to the auxiliary turbine 3! should be interrupted and that to the main turbine restored. When this has been done, the resulting de-energislng of the fluid motor 33 allows the abutment 3| to be depressed. The ahead control sleeve 4| is consequently shifted by the spring 33 to position-As (Figs. 6 and The astem nut 33A now moves to its second position, in which its teeth "A are in mesh with the Jaw clutch teeth 36A of the astern pinion and beyond which it is prevented from moving by the flanking engagement of the dogs A and "A which now co-operate in the same way as did-the dogs 44 and 45 when the head coupling was in the condition shown in Fig. '7. The restoration of the supply of driving fluidto the main turbine causes the propeller shaft 32 to be arrested and thereafter rotated backwards. At the moment when the propeller begins to rotate backwards, the ahead coupling nut 33' will be moved by the action of the pawls 33 and the teeth 33 and from the first position (Fig. 8) to the third position (Fig. 9). Since the control sleeve II has already been shifted to position As (Fig. 10), the nut 33 will overrun the third position and, assisted by the drag due to ratcheting of the pawls III on the teeth 33, will enterthe fourth position in which the pawls are out of the path of these teeth.

The change from astern to ahead working is made similarlyto the change Just described, but in the converse sense.

When the system is at rest, the control lever 33 is in the midposition (Fig. 5) and both control sleeves are in position M. Either ahead or astern drive is established as follows. First the auxiliary turbine 62 is energised soas to rotate the shaft 2| backwards, and as a consequence both coupling nuts will be in the first position, with the pawls 33 and 39A ratcheting over the teeth .33 and 36A respectively. The control lever 53 is now moved to the selected position, say ahead as in Fig. 4. The ahead control sleeve I therefore moves to position Ah (Fig. 7) and the astern control sleeve MA to position F. Next the auxiliary turbine is de-energised and the main turbine is energised so that the shaft 2| begins to rotate forwards. This causes the ahead coupling nut 33 to. move to the second position in which it is held by the co-operation of the dogs 44 and 43', so that the ahead drive is established, while the astern-coupling nut 33A will run through to the fourth position in which it appears in Fig. 1.

In a mechanism accordingto the invention, in which the prime mover is a governed internalcombustion engine, the reversing gearing may be as hereinbefore described, the driving member taking the form of a hollow shaft connected to the runner of a turbo-coupling of the well-known scoop-controlled type fitted with quick-emptying valves, the turbo-coupling impeller being directly gearing shown in Fig. 11 is basically the same as that shown in Fig. 1. and parts in Fig. 11 corresponding to parts shown in Fig. 1 are denoted by the same reference numerals plus I33. Preselective shifting means for the control sleeves HI and IIIA are similar to those shown in Fig. 3. In Fig. 11 the driving shaft III is hollow and rigid with an input coupling flange I'll, forming part of a universal coupling I13, I'll (Fig. 12) of the known type including a flexible ring I II. The flange I'll is integral with ahollow shaft IIB formingthe runner shaft of a scoop-controlled hydraulic turbo-coupling of the kind shown in Fig. 4 of patent specification No. 2,187,667. The impeller I'll of thiscouplingis: bolted to a flange I13 on the engine crank shaft and houses a self-aligning bearing Ill supporting the shaft I16 to which the coupling runner III is fixed.

An. auxiliary drive shaft III passes through the hollow shafts III and I13 and its front end is splined for engagement with an internally splined hub I32 of a driving ring bolted between the flange Ill and the impeller Ill. The rear end of the auxiliary shaft Ill is splined and carries two slidable friction clutch members I33 and Ill co-operating to form a fluid pressure chamber I35. Fluid pressure can be admitted to this chamber through a pipe I33 so as to force the members I33 and I34 apart into frictional engagement with two driven clutch members I31 and I33 forming the body of a gear wheel Ill arranged to drive, through an idler wheel III, a gear wheel I3I fast on the lay shaft I23. The pipe I 36 branches from the pipe I" leading from the control valve I63 to the cylinder I33 of the motor that actuates the abutment I34 of the control mechanism.

In this case the change from for example ahead to astern is effected by biasing the synchro-couplings as described with reference to the example shown in Figs. 1 to 10, disengaging the main hydraulic turbo-coupling and operating the valve I33 to engage the auxiliary friction clutch. The driving shaft III is thereby reversed through the gears I33, I33, I", I33 and III, and the astern synchro-coupling is synchronised and engaged, and thereafter the auxiliary friction clutch is disengaged and the main hydraulic turbo-cow. pling is progressively engaged so that the now backwardly rotating driving shaft III is arrested and finally accelerated in the normal direction to drive the main driven gear wheel III backwards.

The invention may be applied to turbine driven locomotives with mechanical transmission wherein it is desirable when operating a train on long descending gradients to be able to engage the turbine with the drivin wheels of the locomotive through the reverse gear while in forward motion reversegirlve power path, each of said paths having a s ecting clutch disengageable for bidirectiona lly freeing the drives through said paths and engageable for establishing the drives through said paths, auxiliary driving means for rotating said driving member in the reverse direction at a speed of the same order as its normal speed in the forward direction, and control means operable for "energising said auxiliary driving means which, while said driven member is running in consequence of engagement of either one of said selecting clutches, and on disengagement of said one clutch, serve to accelerate said driving member in the reverse direction of rotation to a speed sufllcient to synchronise the other of said selecting clutches.

2. Mechanism as claimed in claim 1, wherein said driving member is the shaft of [a non-reversing] an elastic fluid turbine, and said auxiliary driving means are a separate motor.

3. Mechanism as claimed in claim 1, wherein said driving member is the shaft of [a non-reversing] an elastic fluid turbine, and said auxiliary driving means are a turbine normally rotated idly backwards and capable of being energised for running in its forward direction while it is being rotated backwards by the driv" ing member.

4. Mechanism as claimed in claim 1. and including a prime mover, and a slip coupling having a driving part connected to said prime mover and a driven part constituting said driving memher.

5. Mechanism as claimed in claim 1, and including a prime mover, and a controllable slip coupling having a driving part connected to said prime mover and a driven part constituting said driving member.

6. Mechanism as claimed in claim 1, and including a [non-reversible] reciprocating internal-combustion engine, and a slip coupling having a driving part connected to the crank shaft of said engine and a driven part constituting said driving member.

7. Mechanism as claimed in claim 1, and including a prime mover,,and a slip coupling having a driving part connected to said prime mover and a driven part constituting said driving member, said auxiliary driving means being constituted by a power take-off, including an auxiliary controllable slip coupling, from said prime mover arranged in parallel with the first-mentioned slip coupling.

8. Mechanism as claimed in claim 1, wherein said selecting clutches are of the synchro-selfshifting type having an axially movable intermediate jaw element capable of moving to either side of a position in which it is engaged with a second jaw element, two sets of synchronising pawls which serve to mesh said intermediate jaw element cleanly with said second jaw element when moved from the two sides respectively, and a controllable stop member operable to prevent said intermediate element from moving beyond the engaged position when the driving part of the clutch tends to rotate forwards relatively to its driven part.

9. Mechanism as claimed in claim 1, wherein said selecting clutches are of the synchro-selfshifting type having an axially movable intermediate jaw element capable of moving to either side of a position in which it is engaged with a second jaw element, two sets of synchronising pawls which serve to mesh said intermediate jaw element cleanly with said second jaw element when moved from the two sides respectively, and a controllable stop member operable to prevent said intermediate element from moving beyond the engaged position when the driving part of the clutch tends to rotate forwards relatively to its driven part, each of said intermediate elements-being capable of moving, in response to forward rotation of the driving part of the clutch relative to its driven part. to a disengaged position such that both sets of pawls are inoperative, and the mechanism also including control means for shifting each of said intermediate elements from said disengaged position to a position in which the appropriate one of said sets of pawls is operative.

10. A power-transmission mechanism having a driving member which is [capable of exerting] required to exert substantial driving torque in only a forward direction of rotation, a driven member required to be driven alternatively in the forward and backward directions of rotation at will, gearing providing in parallel between said members a forward-drive .power path and a reverse-drive power path, said paths having respectively two controllable selecting clutches for establishing the drives through said paths, each of said clutches in an inoperative condition permitting relative rotation of its driving and driven parts in both directions, and in an operative condition transmitting forward rotation from its driving part to its driven part, control means operable for biasing said clutches alternatively towards the operative condition, auxiliary driving means for rotating said driving member in the reverse direction, and control means operable for energising said auxiliary driving means which, while said driven member isrunning, serve to accelerate said driving member in the reverse direction to a speed suflicient to synchronise the one of said clutches that was previously inoper ative.

11. A power-transmission mechanism including a main turbine [capable of exerting] required to exert substantial driving torque in only a forward direction of rotation, a driven member required to be driven alternatively in the forward and backward directions of rotation at will, gearing providing in parallel between said turbine and said driven member a forward-drive power path and a reverse-drive power path, said paths having respectively two controllable selecting clutches for establishing the drives through said paths, each of said clutches in an inoperative condition permitting relative rotation of its driving and driven parts in both directions, and in an operative condition transmitting forward rotation from its driving part to its driven part, control means operable for biasing said clutches alternatively towards the operative condition, an

auxiliary motor operable for rotating said turbine in the reverse direction, and control means operable for energising said auxiliary motor and thereby causing, while said driven member is running, said turbine to be accelerated in the reverse direction to a speed sufficient to synchronise the 0211c of said clutches that was previously inopera ve.

12. A power-transmission mechanism including a [non-reversing] motor, a main slip coupling having a driving part connected to said motor and a driven part, a driven member required to be driven alternatively in the forward and backward directions of rotation at will, gearing providing in parallel between said driven part and said driven member a forward-drive powerpatbandareverse-drivepowerpatmsaid' paths having respeotively two controllable selectin; clutches for establishing the drives saidpatbmeachoi'saidclutchesinaninoperative condition permitting relative rotation at its 5' ,drivinganddrivenpartsinbotb directionaand in an operative condition transmitting forward rotation from its driving part to its driven part, control means operable tor biasing said clutches alternatively towards the operative condition, a 10 reverse-drive power take-0H, including an auxiliary controllable slip coupling, between said motor and tire driven part 0! said main slip coupling, and control means operable ior biasing said selecting clutches alternatively towards the 15 Number operative condition.

HAROLD SINCLAIR.

12 nus-sauces crrsn Theioilowingreierenceeamoireccrdintbe file 01' this patent or the original patent.

tmn'sn sum Pam-rs Number Name Date 1,577,101 Beitseil Mar. 16, 1028 1,877,026 Buckland July 10. 1928 2,107,170 Hersey Apr. 16, 1040 2,202,271 Sinclair May 28, 1040 2,252,042 Sinclair Aug. 12, 1041 2,450,861 Oarnagua Jan. 18, 1940 FOREIGN PATENTS Country Date 171.030 Great Britain Nov. 10. 1921 896,822 Great Britain Aug. 10,1933 498,893 Great Britain Jan. 16, 1939' 

